Great question Jesseca.
To me Human aggression in Pit Bulls that occurs naturally (meaning bred in to the dog) is (to me) fear aggression. Fear aggression in any breed is bad. No dog of any breed should be trained (or allowed to live, in my opinion.) that has fear aggression. Bite work is not fear aggression.
Bite work done properly is nothing more than obedience. I call it mouth obedience. You might teach your dog to bite a Frisbee or tennis ball. I am doing the same with my dog and a decoy (bad guy in the suit). When you tell your dog to stop, and drop the ball or Frisbee he will. My protection trained dog will do the same with the decoy.
Later, as time and training go into the dog, we can do much more than the Frisbee or ball dog. We can compete in sports like Schutzhund or Ringsport or if it is so desired by the owner, protect our families and ourselves when the time comes and a real bad guy tries to do us harm. My dogs live with my wife and four children. We have a training business and many friends and family. Our dogs are under control and trained to play a game when asked. Yes, this game can get intense. However, any game can be intense. Control and understanding is key. There is more to bite work to this and I don’t mean (nor do I think) I can get anyone to understand from this small post. Find a qualified trainer and sit in on some classes, read, get videos. Even if you never train for bite work with your dog, seeking knowledge on the topic will help you to understand your breed (and dogs) in a way you never thought possible.
I am fond of saying, “Knowledge replaces fear.” Thanks for taking the first step to get knowledge about bite work! Good for you!